Pneumatic spring.



nNiTnn sTATns PATENT ervaren.

'.PNEUMATIC SPRING.

Specification of Letters Patent.

Patented Aug. 18, 19.14.

Application filed March 14, 1914. Serial No. 824,838.

and the end of the liner Gr. To facilitate To all 'whom it may concernBe it known that I, ARCHIBALD SHARP, its withdrawal from the cylinder,the mitsubject of Great Britain, residing at 231 ten holder may have itsouter end curled Strand, London, W. C., England, have ininward as at (5.A cap A is screwed to the vented certain new and useful improvementsouter end of the cylinder,and is so shaped in Pneumatic Springs, ofwhich the followthat it forms a guide at 7 for the plunger. ing is aspecilication. he screw threads on both the cylinder and rhis inventionrelates to improvements in the cap are preferably rolled, so that thepneumatic springs of the type in which comcylinder and cap may be ofthin metal. pressed air is pumped into a reservoir l/Vhen the cap isscrewed up tight on the formed by a cylinder and hollow plungercylinder, the mitten holder H, the larger each closed at one end and anair tight joint thickened end of the mitten, and the liner is obtainedby the use of a rolling packing G are all pressed tightly together,while the mitten which is extensible radially. rlhe end of the mitten isforced outward against said improvements relate to the methods of thewall of the cylinder making an air-tight arranging and making the parts,including joint therewith.

. those for holding the edges of the rolling The plunger P is made withits normal packing mitten in air tight contact with the externaldiameter at 8 as much less than the cylinder and plunger', wherebygreater seinternal diameter of the mitten holder as is 75 curity andfacility for fastening the mitten required to allow the mitten space toroll is obtained, the parts may be made from thin freely from onesurface to the other. A metal in the form of sheet or tube, and thegroove 9 is rolled onit to receive the smaller working parts may beprotected from accithickened end of the mitten M, while its indentaldamage by rough usage. ner end 10 is expanded to make an easy 80 Figurel is a drawing partly in section, sliding fit in the liner G. Thesmaller thickshowing the invention in its simplest form. ened end of themitten is retained on the i Fig. 2 is a drawing showing a spring havingplunger by the ring R, which is forced the same length and loadsupporting capacdownward b the nut N, squeezing the mitity for a givenpressure of air as that shown ten against t e groove of the plunger,therein Fig. l, but having greater resiliency. by forming an air tightjoint. 'lhe nut N Fig. 3 is a modification of a detail. has its corediameter slightly larger than The cylinder C and the plunger P may thediameter of the plunger at S, and is each be made in one piece drawnfrom sheet screwed on the plunger, the threads on the metal orelectrically deposited, or they may latter being preferably rolled. eachbe made from tube with the end fas- "he cylinder may be knurled at 11and tened air-tight by rolling, beading, brazing, the cap may be knurledat l2, for the pursoldering, or any other convenient method. pose ofobtaining a good hand grip for A loose tubular liner G, is placed insidethe screwing up and unscrewing. A valve V is cylinder' and serves as aguiding surface for fastened to the closed end of the cylinder 95 theinner end of the plunger. A hole is or plunger, coaxially with the saidcylinder drilled in it, or its inner end is notched, so or plunger inthe manner usual with pneuthat the compressed air may pass freely. matictires.

For the purpose of locating it coaxial with If a pneumatic spring isrequired of the the cylinder, a ridge or flange 2 which fits sameeffective diameter and length as that 100 easily inside the cylinder isrolled on it, shown in Fig. l, but containing a larger volwhile itsinner end bears against the end ume of compressed air, part of thecylinder of the cylinder, the contact surface of which may be made oflarger diameter as shown is rounded or conical. The outer end 3 of theby the dotted lines 13. A modilied form of liner is of the samediameter' as its middle construction is shown in Fig. 9., in which 105art A. A distance piece or mitten holder the cylinder is made in twoparts C1 and C.l H fits easily inside the outer end of the cylinsuitablyfastened together air tight at 14, der; its inner end or mouth 5, whichis the outer part C1 being of larger diameter suitably shaped for thepurpose, presses to contain a large volume of air, the inner against thelarger thickened end of the rollpart C, inside which the mitten holderfits,

being flanged outward at 15 to form an ing packing mitten M, squeezingthe said easy fit on the inner part C1. The flange of thickened endbetween the cylinder wall the liner G is an easy fit inside the innerart C. p In some cases the article on which the pneumatic spring is used(for example, the spring fork of a motor bicycle) is provided with astop which limits the movement of the plunger outward from the cylinder,thus preventing any undue stress on the rolling packing mitten. In othercases I may provide an internal stop, one member of which may be formedby a washer 16 fastened to which is detachably fastened to the end ofthe cylinder or plunger by means of the nipple 1S, nut 19 and air tightwasher 20; the other member of the stop is a washer end of the nipple 181s made with a spherical surface, and the end of the plunger may be madewith a spherical surface at 23 or a separate washer may be insertedbetween the plunger end and the valve stem, the said washer having aspherical surface. The said bination a cylinder C and plunger P, eachclosed at one end, a tubular anged liner surfaces fit into correspondingspherical sockets on the parts against which they press. In this way theforces exerted by the pneumatic spring at its two ends, will be coaxial,and there will be little or no lateral pressure on the guiding surfaces7 and 10.

Fig. 3 shows a modification in which the stop washer 21 and nut N arecombined in one piece, which is expanded at 10 to form a working fit inthe liner Cr.

To assemble the pneumatic spring, the nut N is screwed back on theplunger until the ring R is clear of the groove on the plunger. Thesmaller thickened end of the mitten is laid in the groove, the ring Rslipped over it, and the nut N screwed down on the ring. The mitten isfolded on the plunger as shown in F ig. l, the liner G and mittencontact with the larger thickened end of the mitten. The internal stopbeing' in position on the plunger, the parts are then inserted bodily inthe cylinder, and the nut 19 of the mitten to the cylinder and plungerrespectively gives greater security and facility for obtaining air tightjoints therewith, than has been the case formerly.y

Claims:

1. A pneumatic spring comprising in combination, a cylinder C andplunger P, each closed at one end, a tubular iianged liner G, a mittenM, a mitten holder H, a cap A screwed to the open end of the cylinder, aring R, a nut N screwed on the plunger,

`and a valve V coaxial with the cylinder or plunger, the plunger beingadapted to slide lon the liner Cr and cap A.

2. A pneumatic spring comprising in com- G, a mitten M, a mitten holderH, a cap A screwed to the open end of the cylinder, a ring R, a nut Nscrewed on the plunger, a

16 fastened to the cylinder, a washer 21 fastened to the plunger, and arubber buffer 22. 3. A pneumatic spring comprising in combination, acylinder made of an outer part C1 of large diameter and an inner part C2of less diameter, a mitten M, a mitten holder H fitting easily insidethe said part C2, a liner G with a flange fitting easily inside the saidpart C2, a cap A, a plunger P, ring R, nut N, and valve V.

In testimony whereof, I aix my signature in presence of two witnesses.

' ARCHIBALD SHARP. Witnesses:

JNO. MAs'rERToN, IVILLIAM R. SHARP.

Copies of this patent may be obtained for :ve cents each, by addressingthe Commissioner of Patents, Washington, D.

